I have a line stage on the go running VT-25s at about Vp=265VDC / Ip = 30mA.

Right now ICCS is set at ~ 60mA. Vin is about 300VDC and I'll push for as high a Vout as I can so as not to change the operating point of the 10Y more than I need to. I just want to see what sort of influence the shunt regulator will have on the preamp circuit. If it it looks good then next I'll raise the B+ by about 20VDC or so to get your recommended 50V across the CCS. If still good I'll do a newer version on a nice clean board !

35V drop across the reg is still fine. Don't bother raising the reg's Vin in case you like the sound together with your pre. Let us know if it will bring perceivable subjective changes. How did you supply the DHT pre till now? Passive filtering?

I don't think so. This isn't a power stage but I'm driving a line transformer and it seems to sound best in this set up around 30mA. Vp is much lower than some have used. If I remember it right, Larry Moore recommended running the 10Y at 425Vp-k/35mA ! !

Quote:

Originally Posted by Salas

35V drop across the reg is still fine. Don't bother raising the reg's Vin in case you like the sound together with your pre. Let us know if it will bring perceivable subjective changes. How did you supply the DHT pre till now? Passive filtering?

I'm running it in a old chassis that has been used a hundred times. The last few tubes have had to put up with power supplies made from the same old parts. This time it's 350VAC>Bridge> LCLC > One LC per channel> OT primary.
(The only thing purpose built for the 10Y's at this point are the heater supply boards from Rod Coleman which I'd highly recommend. I was running LT108- based current regs before this and am really surprised that you can net such an impressive qualitative improvement from there to here.)

I've noticed that if I set up the Simplistic regs and then shut down, when I fire everything up again the regs just sit there with only the CCS Vref voltage difference below the B+ at the output. I have to play with the trimmers again to get them to move. My first thought is that maybe the regulator doesn't like working straight into the reactance of the OT. I'll try a cap across the output to see if that changes it.
Sound ? It's very good but the shift in the tube's op point is too much to be able to make a flat A-B comparison. Fine detail is everywhere - both structural and tonal - yet no sense of dryness or analytic sound. This is all just impressions but it's my guess if I get them running a little more predictably that they'll be excellent.